Copyholders having document-support surfaces for accommodating multilayered documents are old: U.S. Pat. No. 2,198,356. Where thick multidocument volumes are involved, a mechanism for adjusting the guide line position so that it can be positioned at varying distances is required.
Devices for holding and viewing documents which are fan-folded or which are added to and removed from the holder in sequential fashion have presented problems not addressed by prior copyholders.